Lei points me to this report of unpublished work on the Maori of New Zealand and their relationship to a variant of MAOA and behavior genetics. The piece is a bit garbled and uses hyperbolic terminology, but, it seems that the Maori exhibit a high frequency of an MAOA variant linked to aggression in relation to the basal frequency within the white population. Why would this be? Well, the fact that the Polynesian settlements were often characterized by courageous voyages in search of new lands, and endemic warfare due to constrained resources once settled in those lands, it makes sense that the Maori would exhibit a genetic signature of natural social selection. Anyone who has seen the Maori Haka dance can intuit that these are no pussies. Here is what I said three years ago:

What if we find out that there are different frequencies of the variations of MAOA in diverse human populations? The implications for those who want to see it are clear-what will those of us who believe in equality before the law and the presumption of free will do if we stick our heads in the sand and ignore these possibilities? I don't have the answers, I'm not an ethicist, legal theorist or political philosopher, but those who are might have to begin addressing more controversial topics coming out of neuroscience and genetics sooner than they expect.

We should be cautious about focusing on just one study and one locus, but as the shape of variation across many loci from many studies correlated with many traits begins to emerge we will be able to construct some plausible predictive models.

Addendum: More stuff about the "thrifty gene." I'm on the record about this: fatness is not an adaptation, it is a response eating too much, not exercising, or metabolizing foods in a particular manner, or a combination of these three. Polynesians are grossly fat when introduced to a sugar and refined carb diet, but they weren't always grossly fat. Additionally, there is the hypothesis that they needed to be large and in charge so as to survive those long voyages, but what happens when you arrive in the land of plenty? All of a sudden food is not longer a constraint, shouldn't selective pressure be released all of a sudden?